In the field of motor vehicles, inflatable airbags are often used for the protection of occupants in vehicles in the event of a collision or the like. In the case where such an airbag is used to protect the driver of the vehicle, it is normally arranged in the hub of the steering wheel. In the case where it is used to protect a passenger in the passenger seat of the vehicle, it is normally arranged in connection with the upper part of the dashboard and in front of the passenger seat. Should a collision occur, the airbags are activated by inflating them by means of a gas generator.
In the field of motor vehicles, there is also a need to protect body parts other than the head and the upper torso. The technology forming the basis of airbags may then be employed so as to protect for example knees and legs of vehicle occupants. Following this requirement, devices comprising airbags for use as knee protecting devices have been developed. Such a device is previously known, for example, from U.S. Pat. No. 5,312,131, and comprises an airbag module with two airbags which are arranged under the central console of the dashboard, between the driver's seat and the passenger seat. In the event of a collision, one of the airbags will be inflated in a direction towards the driver, whereas the other airbag will be inflated in the direction towards the passenger.
This known device is associated with a problem due to the fact that it is not arranged so as to take into account how the occupant is seated and the size of the occupant. For example, if an occupant has relatively long legs (or if the occupant has positioned the seat in a far forward position), the airbag will not be positioned between the dashboard and the occupant during inflation, which is the desired procedure, but instead the airbag will impinge on the legs of the occupant from the side. This will result in the legs being pushed away in the sidewards direction, which in turn results in the device not providing the desired protection.
A similar device is previously known from British Patent No. 2,263,671, and comprises an essentially flat airbag forming an elongated unit which is arranged under the dashboard and which extends across the legs of the passenger. A problem with this device is that it is mounted on the outside of the dashboard, which is a disadvantageous position as regards the space available in the vehicle. Furthermore, the airbag is inflated in a direction which essentially forms a right angle with the backing support panel, therefore limiting the possibility of absorbing and distributing the force which acts upon the airbag during a collision.
Another problem in connection with airbag systems for the lower parts of the legs and for the knees is that point-shaped loads often arise, for example during penetration of the occupant's knees in such an airbag. Consequently, there is a risk that, for example, the knees of the occupant are pressed too deeply into the airbag during a collision. This makes it difficult to obtain the desired energy-absorbing effect, especially since an airbag for knees and legs is considerably smaller than a conventional airbag for the upper torso of an occupant, which among other things is due to the fact that the distance between an upper torso airbag and the occupant's upper torso is considerably greater than the distance between an occupant's legs and an airbag designed for the legs.